NASA isn't ready to announce the discovery of life on Mars. At least, not yet.

NASA's Jet Propulsion Laboratory, which is managing the Mars Science Lab mission, tried to dampen ongoing speculation about "major new findings" from the Curiosity rover. The space agency said on Thursday that rumors about a pending announcement of historic significance are incorrect.

Instead, JPL plans to provide a public update on Dec. 3 on the first soil samples taken by the rover's instruments in the search for organic compounds. "At this point in the mission, the instruments on the rover have not detected any definitive evidence of Martian organics," JPL said in a written statement.

But NASA doesn't want to quash all hope for a breakthrough in its mission to discover signs of life on Mars. The mission has already uncovered an ancient riverbed, and "there is every expectation for remarkable discoveries still to come," the agency said.

A minor frenzy was set off on Nov. 20 when a JPL scientist was quoted as saying that Curiosity's Sample Analysis at Mars suite of instruments had uncovered data of such significance that it was "one for the history books."

Since Curiosity landed on Mars in early August, NASA has released scientific findings regularly as the six-wheeled rover rolls along the surface. Among the reports so far: changes in radiation on Mars are linked to daily atmospheric changes; little to no methane gas has been detected; and there's been a loss of atmosphere.

Earlier this week, NASA shared insights on a dust storm on Mars, which it has been monitoring from above using the Mars Reconnaissance Orbiter and on the ground using Curiosity’s Rover Environmental Monitoring Station. Researchers expect those dual observation methods to provide new information about why some dust storms on Mars grow larger than others. In this case, the regional dusk storm is weakening, according to NASA.

In addition to capturing soil and atmospheric samples, Curiosity is generating thousands of images of its journey. They range from mundane pictures of the planet's rock-strewn surface to a self-documentary of the six-wheeled rover and its instruments at work. Pictured above is a composite image, comprised of 55 high-res images, that NASA describes as a "self portrait" of Curiosity. Close observation reveals scoop marks in the sand where the rover's robotic arm took samples.

Some of NASA's images provide new information about Mars, while others raise questions. As the world waits and watches for further discoveries from Curiosity, these pictures in this slideshow show the scientific process at work. Image credit: NASA

Curiosity's robotic arm dug up five scoops of dirt, creating the "bite marks" that are visible in this image. The first scoop was collected on Oct. 7 and the last one two days later. The first two samples were used to "scrub" the inside of the chambers of the robotic arm's sample-handling mechanism, while the remaining scoops were analyzed by the rover's Chemistry and Mineralogy instrument. There had been some speculation that these soil samples had resulted in a discovery of great scientific significance, but NASA says the rumors are false. Credit: NASA

Curiosity's Sample Analysis at Mars (SAM) instrument was at the center of speculation about a breakthrough "for the history books." This picture shows SAM, which is about the size of a microwave oven, as it being assembled at Goddard Space Flight Center. The system includes a tunable laser spectrometer (lower left), a quadrupole mass spectrometer (upper right), and gas chromatograph (lower right). Inlet tubes take in soil samples and powdered rock for analysis. Credit: NASA

This image, taken by the rover's Mars Hand Lens Imager camera, shows a mysterious "bright particle" in the Martian soil. The bright particle, and others similar to it, "prompted concern," according to NASA. At first, mission scientists thought the particle might be a shred of debris from the spacecraft, but they determined it and others were native to Mars. But NASA hasn't really explained just what the material is or what accounts for its light color. Credit: NASA

This shred of debris, about half an inch long, was found by the rover on the surface of Mars. The Curiosity team determined it was left behind by the spacecraft "possibly from the events of landing on Mars." But it's still unclear just where this fragment, which resembles a torn piece of plastic, originated. Credit: NASA

This rock, dubbed "Jake Matijevic" by the Curiosity team, has been a subject of great interest to NASA. Curiosity used several instruments to poke and prod the rock. The red dots show where the rover's ChemCam zapped Jake with a laser, while purple circles highlight points of focus for the Alpha Particle X-ray Spectrometer. The black and white circles indicate where ChemCam looked for pits produced by the laser. Credit: NASA

Curiosity has found evidence of an ancient, flowing stream in several places, including this rock outcropping. The exposed bedrock is comprised of fragments that are cemented together. Scientists theorize that the bedrock was broken up at some point in the past, possibly by falling meteorites. The rounded shape of the gravel indicates it was transported by water and, because of its size, not by wind. Credit: NASA

Here's another outcrop, this one called Link, composed of small, rounded rocks that have been cemented together. According to NASA, water transport is the only process capable of producing the rounded shape of rocks of this size. Credit: NASA

NASA scientists were "surprised" by just how close the similarities are between Mount Sharp, pictured here, and the Grand Canyon. The lower parts of Mount Sharp, which is Curiosity's eventual destination, are composed of rock strata about the same thickness as that of the Grand Canyon. And both have buttes and mesas. Credit: NASA

Curiosity's famous "seven minutes of terror" landing included a rocket-powered descent that used a so-called sky crane. After setting the rover down, the sky crane flew off and fell to the surface. The blue splat in this image (the color has been enhanced) shows what are believed to be multiple impacts from the crash. Smaller dark spots, some distance from the main site, may be secondary impacts from debris that tumbled outward. Credit: NASA

One little known fact about Curiosity is that the tread marks on the rover's wheels leave an imprint in Morse code that spells out "JPL" for Jet Propulsion Lab, which is mission central for the Mars project. The holes in the wheels leave tracks that help the SUV-like vehicle drive more accurately. Curiosity navigates using visual odometry software that measures terrain features to calculate distances as it goes from one location to another. Credit: NASA

This panoramic picture is best viewed on a wide-screen computer monitor. Taken by Curiosity's Mastcam, the view is looking eastward to an area called Point Lake. The rover rolled toward Point Lake after taking the component images used to create this mosaic. The image, like some others from the mission, has been white balanced to show what the scene would look like under the lighting conditions familiar to us on Earth. Link to Full Panorama Credit: NASA